clarify state return values

alert.go

@@ -730,14 +730,20 @@ func (a *AlertNode) restoreEventState(id string) (alert.Level, time.Time) {
 	var anonFound, topicFound bool
 	// Check for previous state on anonTopic
 	if a.hasAnonTopic() {
-		if state, ok := a.et.tm.AlertService.EventState(a.anonTopic, id); ok {
+		if state, ok, err := a.et.tm.AlertService.EventState(a.anonTopic, id); err != nil {
+			a.incrementErrorCount()
+			a.logger.Printf("E! failed to get event state for anonymous topic %s, event %s: %v", a.anonTopic, id, err)
+		} else if ok {
 			anonTopicState = state
 			anonFound = true
 		}
 	}
 	// Check for previous state on topic.
 	if a.hasTopic() {
-		if state, ok := a.et.tm.AlertService.EventState(a.topic, id); ok {
+		if state, ok, err := a.et.tm.AlertService.EventState(a.topic, id); err != nil {
+			a.incrementErrorCount()
+			a.logger.Printf("E! failed to get event state for topic %s, event %s: %v", a.topic, id, err)
+		} else if ok {
 			topicState = state
 			topicFound = true
 		}

services/alert/api.go

@@ -226,11 +226,15 @@ func (s *apiServer) createClientTopic(topic string, state alert.TopicState) clie
 }
 
 func (s *apiServer) handleTopic(id string, w http.ResponseWriter, r *http.Request) {
-	state, err := s.Topics.TopicState(id)
+	state, ok, err := s.Topics.TopicState(id)
 	if err != nil {
 		httpd.HttpError(w, fmt.Sprintf("failed to get topic state: %s", err.Error()), true, http.StatusInternalServerError)
 		return
 	}
+	if !ok {
+		httpd.HttpError(w, fmt.Sprintf("unknown topic: %q", id), true, http.StatusNotFound)
+		return
+	}
 	topic := s.createClientTopic(id, state)
 
 	w.WriteHeader(http.StatusOK)
@@ -294,9 +298,13 @@ func (s *apiServer) handleListTopicEvents(topic string, w http.ResponseWriter, r
 
 func (s *apiServer) handleTopicEvent(topic string, w http.ResponseWriter, r *http.Request) {
 	eventID := path.Base(r.URL.Path)
-	state, ok := s.Topics.EventState(topic, eventID)
+	state, ok, err := s.Topics.EventState(topic, eventID)
+	if err != nil {
+		httpd.HttpError(w, fmt.Sprintf("failed to get event state: %s", err.Error()), true, http.StatusInternalServerError)
+		return
+	}
 	if !ok {
-		httpd.HttpError(w, fmt.Sprintf("event %q does not exist for topic %q", eventID, topic), true, http.StatusNotFound)
+		httpd.HttpError(w, fmt.Sprintf("unknown event %q in topic %q", eventID, topic), true, http.StatusNotFound)
 		return
 	}
 	event := client.TopicEvent{

services/alert/service.go

@@ -457,12 +457,12 @@ func (s *Service) UpdateHandlerSpec(oldSpec, newSpec HandlerSpec) error {
 }
 
 // TopicState returns the state for the specified topic.
-func (s *Service) TopicState(topic string) (alert.TopicState, error) {
+func (s *Service) TopicState(topic string) (alert.TopicState, bool, error) {
 	t, ok := s.topics.Topic(topic)
 	if !ok {
-		return alert.TopicState{}, fmt.Errorf("unknown topic %q", topic)
+		return alert.TopicState{}, false, nil
 	}
-	return t.State(), nil
+	return t.State(), true, nil
 }
 
 // TopicStates returns the max alert level for each topic matching 'pattern', not returning
@@ -472,12 +472,13 @@ func (s *Service) TopicStates(pattern string, minLevel alert.Level) (map[string]
 }
 
 // EventState returns the current state of the event.
-func (s *Service) EventState(topic, event string) (alert.EventState, bool) {
+func (s *Service) EventState(topic, event string) (alert.EventState, bool, error) {
 	t, ok := s.topics.Topic(topic)
 	if !ok {
-		return alert.EventState{}, false
+		return alert.EventState{}, false, nil
 	}
-	return t.EventState(event)
+	state, ok := t.EventState(event)
+	return state, ok, nil
 }
 
 // EventStates returns the current state of events for the specified topic.

services/alert/types.go

@@ -16,15 +16,15 @@ type HandlerSpecRegistrar interface {
 	HandlerSpecs(pattern string) ([]HandlerSpec, error)
 }
 
-// Topics is responsible for querying  the state of topics and their events.
+// Topics is responsible for querying the state of topics and their events.
 type Topics interface {
 	// TopicState returns the state of the specified topic,
-	TopicState(topic string) (alert.TopicState, error)
+	TopicState(topic string) (alert.TopicState, bool, error)
 	// TopicStates returns the state of all topics that match the pattern and have at least minLevel.
 	TopicStates(pattern string, minLevel alert.Level) (map[string]alert.TopicState, error)
 
 	// EventState returns the current state of the event.
-	EventState(topic, event string) (alert.EventState, bool)
+	EventState(topic, event string) (alert.EventState, bool, error)
 	// EventStates returns the current state of events for the specified topic.
 	// Only events greater or equal to minLevel will be returned
 	EventStates(topic string, minLevel alert.Level) (map[string]alert.EventState, error)
@@ -46,7 +46,7 @@ type Events interface {
 	// UpdateEvent updates an existing event with a previously known state.
 	UpdateEvent(topic string, event alert.EventState) error
 	// EventState returns the current events state.
-	EventState(topic, event string) (alert.EventState, bool)
+	EventState(topic, event string) (alert.EventState, bool, error)
 }
 
 // TopicPersister is responsible for controlling the persistence of topic state.